Nematospiroides dubius in the mouse: evidence that adult worms depress the expression of homologous immunity

Summary Mice immunized by a single infection with irradiated (25 krad) larvae of N. dubius were very resistant to subsequent challenge. However, when normal larvae were administered together with irradiated larvae at immunization, the acquired immunity expressed against a challenge infection was markedly depressed. It was found that as few as 50 normal N. dubius larvae interfered with the immunity that would have otherwise been elicited by the concurrently administered irradiated larvae, but this depressed response was totally alleviated when the normal worms were removed after completing their development in the intestinal mucosa and before they reached adulthood. Adult TV. dubius were transplanted directly into the intestines of mice either 7 days before or after immunization by irradiated larvae; it was shown that the recipient mice were less resistant to challenge than mice which had been sham operated. Transplanted adult worms themselves stimulated very little resistance to challenge in recipient mice. These results established that adult parasites are capable of depressing the expression of homologous immunity in the mouse. The possible mechanisms by which JV. dubius might modulate the host's immunological activity at the intestinal level are discussed and it is proposed that this mechanism is of benefit to the parasite in preventing the host from eliminating the worms during a chronic primary function.     

Patient Characteristics Associated with Retention in a Methadone Maintenance Program

The purpose of this study was to determine if it is possible to differentiate between types of patients as to their ability to stay in a methadone maintenance program. Since medical and counseling staff cannot work with ail patients simultaneously, such information would be helpful in identifying who needs the most help. This study is based on most admissions (679 cases) to the Dole-Nyswander methadone maintenance program from its initiation in 1964 to 15 March 1968. Each patient was followed-up to determine whether they were still in the program 2 years later. This meant the last admissions were followed to 15 March 1970. Eighty percent of both males and females were continuously in the program for 2 years or longer. (1) As expected, those patients who did poorer were those who, had longer conviction records, were multiple drug users, abused alcohol, were not employed at admission, were older and were not married. (2)Other factors that were expected to be related to program stay, but proved to have little or no relationship were; age when started using heroin, number previous hospitalization, length of education and longest job held. (3)Patients with relatively short usage or very long usage did better than those in the middle range (8 to 19 years of use). (4)When clinical experience was used as a guide for combining single factors some interesting classifications of patients emerged. For example, the best group were those who were abusers for 5 years or less and had no multiple drug or alcohol abuse. This group had a 96 percent outcome rate. The poorest group were those who had 12 to 15 years of abuse and 7 or more convictions. This latter group had 58 percent in program 2 years after admission. (5)When the single factors were combined by using configural analysis, a somewhat different patient classification was developed. The patient types had outcome rates which ranged from 56 to 94 percent.